Process of making printing-plates.



NITED STATES PATENT OFFICE.

EMIL LEITNEB, 0F HOBOKEN, NEW JERSEY, ASSIGNOR TO POWERS PHOTO ENGRAVING COMPANY, ,OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF MAKING PRINTING-PLATES.

No Drawing.

To all whom it may concern:

Be it known that I, EMIL LEITNER, a subject of the Emperor of Germany,having declared my invention. of becoming a citizen of the United States, residing at Hoboken, inthe county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Processes. of Making Printing-Plates, of which the following is a specification.

The invention relates to the, production of photo mechanical printing plates, and more especially to the production of such plates by the half-tone process.

Objects of the invention are to produce plates of the best quality, rapidly and economically, and to produce clear high lights in the plate, entirely free from the half.- tone dots or like screen figures without hand tool work, or other means outside of direct process work; to provide for the production of such clear high lights in the high relief parts of the work, while leaving the remainder of the work totally unaffected, showing the deep shadows, and the intervening tones or grades up to the high lights in their true values as produced from the picture or other original in the usual process. These and other objects of invention will in part be obvious and in part will be set forth hereinafter.

The invention consists in the novel steps, processes, combinations and improvements herein shown and described.

In the preferred form for carrying out my invention and considering same as applied in the production of a copper halftone printing plate, the original of what soever kind is photo aphed in the camera with the interposition of the half tone screen, producing the usual half-tone negative. The copper plate is sensitized in the usual manner, as by applying thereto a coating of bi-chromated albumin, that is al-- bumin having mixed therewith a suitable salt, such as ammonium di-chromate, said coating being whirled and dried upon the plate. 1

The copper plate may then be exposed beneath the halftone negative in the usual manner and developed. After develo ment the plate in the case of the ename top plate, is heated or burnedff and afterward Specification of Letters Patent. v Patented Oct, 16, 1917,

Application filed February 10, 1914. Serial No. 817,913.

it is given the first or shallow etching, in the usual manner.

The plate at this time is in the usual condition of half-tone plates, showing the high lights as grays of the lightest tone or shade in the picture or design. I next and with a view to eliminate the grays from the high lights and to produce the high lights as a pure White in the plate and imprints therefrom, roll up the plate in a heavy or still ink, such as lithographers ink. To the plate so rolled up, I apply powdered dragons blood, applying it thoroughly over the rolled up surface. I do this pref erably by brushing it in in a plurality of directions, as by brushing it four ways, that is by brushing it both backward and forward in each of two directions. It may be thoroughly applied in other ways so far as concerns many features of the invention.

I then remove the dragons blood from the high lights, that is, the high reliefs of the plate, in a suitable manner and preferably by a current of air, that is, by blowing oif the powdered dragons blood. The current of air may be supplied from a bellows or blower and is regulated and directed so that the powder is blown only from the high reliefs, and is left superimposed upon the lower parts of the plate, that is, those parts of the plate representing the intermediate tones all the way from the tones next the high lights to the full shadows. The dragous blood acts as an acid resist to the subsequent etching. The powdered dragons blood is then burned in by heating the plate until the powder is thoroughly melted and reduced to a condition wherein it forms an acid resistant coating over all the plate except the high lights from which it has been blown off.

The plate is then given a deep etching preferably with a solution of iron perchlorid. This etching, however, aflects or acts only upon those portions of the plate from which the powdered dragons blood has been blown, the remaining portions of the plate being protected from the action of the etch by the coating of melted dragons blood. As a result of such etching, the half-tone dots or like screen figures are entirely eliminated from the high lights which are thus left a clear white.

sary or desirable, I again apply to .the plate the powdered dragons blood and again blow it -from the high lights or high reliefs on the plate all which may be done substantially as already described. The second application of powdered dragons blood is burned in as before and the plate is given another deep etching.

The plate may then be cleaned and otherwise prepared for printing, but no routing or hand tooling will be required to produce clear high lights, as by my process the same are produced so as to give results of the highest quality.

It will be understood that variations may be made from the precise manner of carrying out the. steps and processes as described, within the scope of the accompanying claims, without departing from the principles of the invention and without sacrificing its chief advantages.

What I claim as my invention and desire to secure by Letters Patent is 1. The process of producing a photo-mechanical printing plate having clear high lights which comprises making a half-tone plate, applying an acid resistant material to the half tone surface, removing said acid resistant material from a vportion of the plate by. means of a fluid under pressure,

and etching out the halttone screen figures from the parts of the plate from which the acid resistant material was removed.

2. The process of producing a photo-mechanical printing plate having clear high lights which comprises making a halftone plate, rendering an acid resistant material slightly adherent upon said half-tone surface, removing said acid resistant material from a portion of said surface by the action of an air current, and deep etching the portions of the halt-tone surface so exposed.

3. The process of producin a photo-mechanical, printing plate with clear high lights which comprises making a halt-tone plate,rendering an acid resistant powder slightly adherent upon the face of said plate,

' directing a current of air against said plate so as to blow the adherent powd r 03 from the high parts of the plate while leaving it still adherent upon the lower parts of the plate, melting the powder remaining-adherent upon the lower portions of said plate, and etching the dots or other screen figures out of said exposed high parts of the plate.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

El /EL LEITNER.

Witnesses JOHN D. MORGAN, JOHN W. SNYDER. 

